Projection mapping is often a very complicated process due to the careful alignment of projectors required to align numerous two-dimensional (“2D”) projected images onto a three-dimensional (“3D”) surface. Hence, the pose of each of the projectors relative to the surface needs to be calibrated, which is often performed using cameras acquiring images of the physical object as a projector is projecting many calibration test patterns (e.g. structured light patterns) onto the surface. For example, the structured light patterns generally comprise a series of binary patterns that enable the position of projector pixels to be found on the surface. The number of calibration test patterns may number in the tens or hundreds or more and hence a calibration may take a considerable amount of time to implement. In particular, images of the structured light patterns on the surface, captured by a camera, may be compared with the actual structured light patterns to determine a geometry of the projectors with respect to the surface and/or the geometry of the surface. When a system undergoes perturbation or drift, then it needs to be corrected, or calibrated, again; such perturbation or drift may occur due to thermal effects and/or the projector and/or the camera and/or a surface onto which the projector is projecting being moved slightly. However, interrupting a projection mapping show to perform a full calibration using a full set of ten or more test patterns may be unacceptable.